<input type="text" size="10" value="" id="startDate"/> to <input type="text" size="10" value="" id="endDate"/>
<script type="text/javascript">
    function customRange(input) {
        return {minDate: (input.id == "endDate" ? $("#startDate").datepicker("getDate") : null),
            maxDate: (input.id == "startDate" ? $("#endDate").datepicker("getDate") : null)};
    }
</script>